摘要
【目的】研究异形喷嘴水滴直径、速度及动能的分布规律。【方法】采用视频雨滴谱仪对PY15摇臂式喷头在100、150、200、250、300k Pa共5个工作压力下进行室内无风水滴分布试验。【结果】等流量喷嘴的射程:圆形>菱形>椭圆;异形喷嘴的形状系数随出口直径增加而减小,随长径比增加而增大;菱形喷嘴水滴直径沿径向增大的趋势最大。【结论】形状系数越大,相同工作压力下的末端水滴直径越小。出口直径越大,射程越远,水滴速度随直径增加的幅度越大。长径比越大,射程越近,水滴平均直径和速度越大。随水滴直径增大,椭圆形喷嘴的水滴速度增幅最小。相同位置处的单位体积水滴打击动能及增长幅度随压力增大而减小。水滴直径和水滴动能沿径向分别呈指数函数和线性函数关系,水滴速度与直径呈对数分布,3个水滴分布预测模型拟合系数都在0.9以上,可以用来模拟异形喷嘴喷头的形状系数、出口直径、长径比与水滴分布特性的关系。
【Objective】The distribution of water droplet diameter of the sprinkler nozzle is an important parameter in designing sprinkler irrigation.The purpose of this paper is to study how non-circular nozzles affect this distribution.【Method】We studied two non-circular nozzles:an rhombic nozzle and an elliptical nozzle.By keeping the spraying rate the same,we compared the distribution of water droplet diameters of each nozzle using the PY15 rocker arm by keeping the working water pressures in the range of 100 to 300 kPa.For each test,we measured the distribution of the droplet diameters using a video raindrop spectrometer,with that measured from round circular nozzle taken as the control.【Result】The diameter of coverage of all nozzles was ranked in the order of round>rhombic>elliptical.Shape coefficient of the non-circular nozzle decreased as the outlet diameter of the nozzle increased while increased as the length-diameter ratio increased.The diameters of water droplets of the rhombus nozzle increased most quickly in the radial direction,compared to the other two nozzles.When working water pressure was the same,the diameter of the end-water droplet decreased as the shape coefficient of the nozzle increased;the diameter of the coverage increased with the diameter of the nozzle outlet.Increasing the outlet diameter can speed up the droplet velocity,while increasing the diameter-length ratio reduces the maximum distance that the droplets can reach due to the increased droplet diameter and velocity.The increase in droplet velocity of the elliptical nozzle with droplet diameters was the least.The kinetic energy and the increase in amplitude of unit volume of the droplets at the same location both decreased as the working water pressure increased.The diameter and kinetic energy of the droplets increased with the radial distance exponentially and linearly,respectively,while the relationship between velocity and diameter of the droplets was logarithmic.【Conclusion】Geometrical shape of the sprinkler nozzle has a significant impact on the diameters of the water droplets and their spatial distributions.
作者
刘佳玲
万吉祥
李浩
蒋跃
LIU Jialing;WAN Jixiang;LI Hao;JIANG Yue(Chinese Academy of Agricultural Sciences,Farmland Irrigation Research Institute/Henan Province Water-saving Agriculture Key Laboratory,Xinxiang 453002,China;Jiangsu University the Research Center for Fluid Mechanical Engineering Technology,Zhenjiang 212013,China;Suqian Water Resources Bureau,Suqian 223999,China)
出处
《灌溉排水学报》
CSCD
北大核心
2021年第12期85-92,118,共9页
Journal of Irrigation and Drainage
基金
国家自然科学基金项目(51809119)
河南省节水农业重点实验室开放课题(FIRI202001-0101)。